Hi I'm from Mexico and pedi Smartaddons helps to solve a problem I had with the logging system in Joomla! (did not close the session of the user in the frontend), fixed, however after I appeared another error (see picture), and no response was, in almost every forum you have here, no one could give the solution until I found the solution.
We just have to disable Logoff Plugin Joomla!
Sorry for English I'm using Google translator, leave a picture more to deactivate this plugin